This application claims the priority of Ser. No. 10-178383, filed Jun. 25, 1998, the disclosures of which is expressly incorporated by reference herein.
The present invention relates to a testing system and a testing method for a structure, and more particularly to a testing system and a testing method for a structure which can be preferably used for an earthquake resistance test.
To evaluate the earthquake resistance of a structure, it becomes necessary to evaluate not only the linear deformation of the structure but also the non-linear deformation and the rupture phenomenon of the structure. For this purpose, a testing method where a test is carried out by combining the simulation of the behavior of the structure using a computer and a shaking test which actually shakes a test piece using a shaking table and an actuator has been put into practice. This testing method has an advantage that it can carry out the test using the test piece which has a size close to a size of an actual structure. However, since both the actuator and the test piece are mounted on the shaking table, the actual situation is that the test piece which is mounted on the shaking table must be small-sized compared to the size of the shaking table. Conventionally, at the time of testing a structure, the test piece, the actuator for shaking the test piece and a reaction wall for the actuator are all mounted on the shaking table. Such an example is described in JP-A-7-55630.
As described above, in the test which combines the simulation using the computer and the shaking test which tests the actual test piece using the shaking table and the actuator, the test can be carried out using the test piece having the size similar to that of the actual structure. However, in the testing method described in the known example which mounts the reaction wall for the actuator on the shaking table the part of the shaking table is occupied by this reaction wall. Accordingly, only the remaining part of the shaking table can be used for the test piece so that such a method is less optimal in view of the effective use of the shaking table. Therefore, the advantage that the large structure can be tested is hampered and thus reducing the space for the reaction wall is required in terms of the preparation of the expensive shaking table facilities.
The present invention has been made to solve the above mentioned. inconveniences and it is an object of the present invention to provide a testing system and a testing method which can sufficiently make use of the size of the shaking table and can carry out a test on a test piece having a size close to a size of an actual structure.
It is another object of the present invention to provide a testing system and a testing method for a structure which can make use of an entire space of the shaking table. Furthermore, the present invention can achieve the above objects with a simple constitution without adding any comprehensive modifications to a shaking table device. According to one aspect of the present invention to achieve the above objects, a testing system is disclosed for which tests a structure made of a partial structure and a numerical model virtually connected to this partial structure. The test system includes a shaking table on which the partial structure is mounted. A simulated structure is also provided and includes an actuator for shaking the partial structure. A reaction force measuring means measures a reaction force received from the partial structure when the partial structure is shaken. A digital computer calculates the motion of the numerical model based on the measured values of the reaction force measuring means and generates a shaking signal for the actuator based on the calculated result. The shaking table and the simulated structure are mounted on a same foundation.
According to another aspect of the present invention the testing system comprises a shaking table which is mounted on a foundation by way of a first actuator. A simulated structure having at least one second actuator which is fixedly mounted on a foundation which is common to the foundation on which the shaking table is mounted. A reaction force measuring device measures a reaction force generated by a test piece structure connected to the simulated structure. A digital computer stores a numerical model virtually connected to the test piece structure. A controller which controls the simulated structure and a shaking table motion measuring device measures the motion of the shaking table.
In a preferred embodiment the digital computer outputs a control signal to the controller based on outputs of the shaking table motion measuring device and the reaction force measuring device. It is also preferable that the digital computer calculate the motion of the test piece structure based on the output of the reaction force measuring device and the numerical model, and includes an adder which adds the calculated result and the output of the shaking table motion measuring device, and outputs the added result to the controller.
Yet further the digital computer may stored the shaking wave form of the shaking table, and outputs a control signal to the controller based on the output of the reaction force measuring device. The digital computer includes time control means which controls a shaking timing of the shaking table.
It has a plurality of degrees of freedom further preferable that the simulated structure is for shaking.
It is also preferable that the digital computer includes memory means to which the numerical model is inputted, structure motion calculating means which calculates the motion of the structure after a predetermined period from the time when the reaction force is measured based on the outputs of the reaction force measuring device and the shaking table motion measuring device with reference to the numerical model stored in the memory means. A shaking signal calculating means calculates a shaking signal to be given to the actuator after a predetermined period based on the calculated motion of the structure, and time control means which controls the predetermined time.
Futhermore, the digital computer may include means for storing the shaking wave form of the shaking table, while the time control means controls the shaking timing of the shaking table based on this stored shaking wave form.
According to another aspect of the present invention a testing method for a structure is disclosed which tests a structure made of a partial structure and a numerical model virtually connected to this partial structure. The partial structure is mounted on a shaking table and is shaken by the shaking table. An actuator is fixedly mounted on the same foundation on which the shaking table is mounted. A reaction force generated by the partial structure and a displacement of the shaking table this then measured and a motion of a joint between the numerical model and partial structure after a predetermined period from the time when the reaction force is measured is obtained based on the measured values of the reaction force and the displacement of the shaking table. A shaking signal is inputted to the actuator for realizing the obtained motion at the joint after a lapse of the predetermined time and the actuator shakes the partial structure based on this signal.
According to another aspect of the present invention a testing method is disclosed for a structure made of a test piece structure mounted on a shaking table and a numerical model virtually connected to the test piece structure and stored in a digital computer. A step is included in which the test piece structure is shaken by the shaking table and an actuator fixedly mounted on a foundation on which the shaking table is mounted, and a reaction force generated by the test piece structure is measured. In a further step a displacement of the shaking table is measured. The measured value of the reaction force displacement of the shaking table is inputted to the digital computer. In a future step a relative motion of the structure to the shaking table after a predetermined period from the time when the reaction force as measured is calculated from the measured value of the reaction force with reference to the numerical model. In a subsequent step a relative motion of the structure to the foundation for the shaking table after a predetermined period from the time when the reaction force is measured is calculated by adding the calculated result of the relative motion of the structure and the measured value of the displacement of the shaking table. Thereafter a shaking signal which makes the motion obtained by the calculation at a portion of the test piece structure to be shaken by the actuator is calculated. The shaking signal is outputted after a predetermined period from the time when the reaction force is measured, and a step in which the actuator is driven based on the shaking signal are carried out in sequence.
According to another aspect of the present invention a testing method is disclosed for a structure made of a test piece structure mounted on a shaking table and a numerical model virtually connected to the test piece structure and stored in a digital computer. The test piece structure is shaken using the shaking table and an actuator fixedly mounted on a foundation on which the shaking table is mounted. A reaction force generated by the test piece structure is measured and inputted to the digital computer while a relative motion between the structure and the shaking table after a predetermined period from the time when the reaction force is measured is calculated using the measured value of reaction force with reference to the numerical model. A relative motion of the structure to the foundation for the shaking table after a predetermined period from the time when the reaction force is measured is calculated by adding the calculated result of the relative motion of the structure and a preliminarily obtained displacement of the shaking table. A shaking force given to the test piece for making the calculated motion after the predetermined period is obtained, and this shaking force is generated by the actuator.
The preliminarily obtained displacement of the shaking table is preferably measured at the time of measuring the reaction force or prestored in the digital computer. It is also preferable that the preliminarily obtained displacement of the shaking table is the value measured at the time of measuring the reaction force. After calculating the relative motion between the structure and the shaking table which is carried out after a predetermined period from the time when the reaction force is measured, when the motion of the structure relative to the foundation for the shaking table after a predetermined period is to be obtained, a prestored shaking wave form of the shaking table is used. The time lag is calculated from the difference between the measured value of the motion of the shaking table and the prestored wave form and the predetermined period is adjusted based on the time lag to correct the predetermined period.